To be fair all of these reasons come down to personal preference (sans the TCP performance claim). E.g. he prefers FreeBSD’s performance monitoring tools to Linux’s monitoring tools, or he prefers FreeBSD’s user land to Linux’s user land. That’s fine but it’s not very persuasive.

vmstat -z gives me counters of kernel limit failures on FreeBSD. Very useful when debugging errors in very high performance environments. Anybody knows what the Linux equivalent is? Say I need to know how many times file descriptor/network socket/firewall connection state/accepted connection limits were reached?